Gene expression in limited cutaneous SSc skin

Systemic sclerosis (SSc) is an autoimmune disease characterized by clinical heterogeneity, multi-organ involvement, and complex genetic risk. Here, we report the first multi-tissue meta-analysis of ten independent SSc gene expression datasets. We identify a common immune-fibrotic expression axis across all tissues that is associated with the most severe disease phenotypes. The coexpression patterns conserved across tissues and phenotypes were used to query functional genomic networks, which allowed us to identify common and tissue-specific disease drivers. We find evidence of pro-fibrotic macrophages (MØs) in SSc end-target organs. Prominent genes in the skin functional genomic network are associated with SSc genetic risk and are modulated by immunosuppressive treatment in clinical improvers. These data suggest the interactions between T lymphocytes and MØs are a critical driver of disease and implicate MØs as central to SSc pathogenesis. In total, this study presents a mechanism for fibrosis in SSc end-target tissues, a set of putative therapeutic targets for modulating SSc, and a framework for multi-tissue functional genomic studies of complex human disease. Gene expression was measured in forearm skin punch biopsies in 10 limited cutaneous systemic sclerosis patients and 5 healthy controls